1. Field of the Invention
This is process relates to metal and non-metallic machining, specifically extending the capabilities of existing machine tools.
2. Description of the Related Art
Extending the capability of machine tools to provide a better return on capital investment is an industry within itself. The proliferation of add on devices such as tapping heads, speed increasers, probes, etc. is well documented. The means to power the accessories range from using the rotating spindle of the machine tool, air, and in some cases hydraulic power.
The rotating spindle power is the most common power source for accessories. The accessory is normally constructed with a rotary joint that allows the machine tool to provide rotary power input to the device while the main body of the device is held steady by means of a lever arm placed against a non-rotating surface of the machine tool. In many instances secondary operations such as light broaching will effect the capability of the machine tool to hold close tolerances while doing its primary work of milling, and drilling.
Shop air pressure has been used to power high speed, low power output rotary spindles in some applications. Typically an air turbine is attached to the spindle and an air supply hose is attached to shop air for power. The turbine rotates at high speed to machine aluminum and composites. The higher speed spindle allows smaller tools to operate closer to their recommended surface feed rates. Although air operated rotary spindles can develop high speed, they do not provide high torque and due to the compressibility of air, the spindle speed varies greatly with the cutting load. This has a severe impact on the costs of manufacturing because the inability to use the maximum machine tool feed rates increases machining time. The use of air power equipment for machine accessories has never progressed in the marketplace much beyond specialty air powered rotary spindles.
Attachable hydraulic spindles have been used in rare occasions to increase the speed of rotary machine tools. The hydraulic spindle uses conventional high pressure hydraulic pumps to power a turbine that is attached to the spindle of the machine tool. Hoses connect the pump to the attached turbine. These spindles provide high torque at relatively high speeds. The main objection to the use of hydraulics for powering accessories is that hydraulic systems tend to leak. Leaking hydraulic fluid can mix with the machine tool coolant, thereby contaminating the coolant supply and causing problems with separation and disposal of the coolant.
The use the of coolant flow to provide power at the spindle solves the problems of the other methods employed to power machine tool accessories. The coolant is available at the machine tool sump and commercially available pumps can be attached directly to the machine tool with little modification. The incompressibility of the liquid coolant affords higher power output than air powered devices and the problem of hydraulic oil powered devices contaminating the coolant is avoided.
All forms of motion can be produced with the coolant as a power source. Uses of this power source includes but are not limited by mechanisms that tap, countersink, drill, deburr, mill, and broach. One application for this technology has been prototyped, tested, and redesigned by the applicants. The device is used to allow the machine tool to make accurate countersinks, and blind holes from cast surfaces without probing the surface or changing the tool offsets.
For a more complete understanding of the above and other features of this technology, reference should be made to the following detailed description of a preferred embodiment and to the accompanying drawings.